There has been continuing effort to develop new types of high performance polymeric compositions which exhibit high heat and oxidation resistance and improved mechanical properties.
U.S. Pat. No. 3,264,536 describes a novel type of solid thermoplastic polyarylene polyether which is adapted for incorporation in an electric capacitor as a dielectric. The preferred linear thermoplastic polyarylene polyethers are prepared in an essentially equimolar one-step reaction of a double-alkali salt of a dihydric phenol with a dihalobenzenoid compound in the presence of specific liquid organic sulfoxide or sulfone solvents under substantially anhydrous conditions.
U.S. Pat. No. 3,332,909 discloses a type of organic polymers which have ether oxygen atoms valently connecting together aromatic nuclei or residua or aromatic compounds: EQU -- O -- G -- O -- G' --
wherein G is the residuum of a dihydric phenol, and G' is the residuum of a dibromo or diiodobenzenoid compound.
U.S. Pat. No. 3,375,297 provides novel linear thermoplastic polymers which are polyhydroxyethers having the formula: EQU -- O -- D -- O -- D' ).sub.n
wherein D is the residuum of a dihydric phenol, D' is a hydroxyl containing residuum of an epoxide, and n represents the degree of polymerization and is at least 30 and is preferably 80 or more.
U.S. Pat. No. 3,516,966 describes a type of film and fiber forming copolyketone polymer consisting essentially of the recurring structural unit: ##STR1##
U.S. Pat. No. 3,809,682 provides an improved process for the manufacture of aromatic polyethers and polythioethers by treatment of the alkali salt of a divalent aromatic phenol or an aromatic dimercapto compound with an aromatic dihalogen compound in a polar solvent.
U.S. Pat. No. 3,678,006 discloses a new class of polyphenylene copolymers, tripolymers and quaterpolymers modified with an alkyl and/or aryl phenolic compound and/or aromatic amine curable to useful coating, bonding and molded resins with curing agents generally applicable to phenolic resins.
U.S. Pat. No. 3,886,120 and 3,886,121 describes a process for preparing polyarylenepolyether polymers of the formula: EQU -- E -- O -- E' -- 0 --
wherein E represents a residual divalent phenol group and E' represents a residual benzenoid group having a weak electron withdrawing group in at least one of the positions ortho or para to the valence bonds.
The high performance polymers known in the prior art generally undergo thermal changes at a molding temperature higher than 300.degree. C. Polyaromatic polymers often become discolored under high temperature melt conditions, so that transparency is reduced and light-transmittance of the polymeric mass is lowered. Further, high performance polymers which exhibit high temperature stability are deficient with respect to other desirable properties such as flexibility and solubility in solvents.
Accordingly, it is an object of this invention to provide a novel class of high performance polymers which exhibit improved melt stability, flexibility, transparency and appearance.
It is another object of this invention to provide polyester resins which are thermally stable at temperatures up to about 400.degree. C, and which are solvent soluble.
It is a further object of this invention to provide polyester resins which contain polyphenyl ether blocks, and which can be melt extruded or molded at temperatures between about 350.degree. and 400.degree. C.
Other objects and advantages of the invention shall become apparent from the following description and examples.